Implantable cardiac pacemakers in their basic known form have housings in which a battery is situated, which allows operation of the pacemaker over many years. The battery powers a pacemaker controller, which is typically connected to a detection stage for cardiac signals and to a stimulation pulse generator. Both the stimulation pulse generator and also the detection stage for cardiac signals are in turn connected to terminals for one or more electrode lines, which allow stimulation pulses generated by the stimulation pulse generator to be delivered to the muscle tissue of the heart (myocardium) or electrical potentials in the heart to be detected and processed.
The different modes of operation and variations of such cardiac pacemakers are known in principle and do not need to be explained further here. The mode of operation of a pacemaker is characterized by a standardized letter code. In the framework of this standardized nomenclature, a DDD pacemaker is a pacemaker which may deliver stimulation pulses to both the ventricle and also to the atrium, which may additionally detect electrical potentials both in the ventricle and also in the atrium, and which finally may be operated inter alia in a demand mode, in which stimulation pulses are only delivered to the ventricle or to the atrium when this is required, i.e., when an electrical potential accompanying a natural contraction of the atrium or ventricle is not detected within a ventricular or atrial escape interval. If a natural cardiac contraction is detected during the duration of the escape interval, the delivery of a corresponding stimulation pulse is suppressed (inhibited). A pacemaker which is capable of stimulating the atrium in the demand mode is referred to as an AAI pacemaker. The first letter describes the capability of the pacemaker of delivering stimulation pulses to the atrium, the second letter describes a capability of the pacemaker of detecting atrial cardiac actions, and the third letter describes the capability of the pacemaker of suppressing the delivery of an atrial stimulation pulse if a natural cardiac action is detected within a set interval, typically referred to as an escape interval. Correspondingly, a pacemaker which may stimulate the ventricle in the demand mode is referred to as a VVI cardiac pacemaker.
Known cardiac pacemakers are typically implanted beneath the clavicle of a patient. The connection to the heart is produced via flexible electrode lines, which end in the particular chamber of the heart (atrium or ventricle) and are provided with electrodes there. On the pacemaker side, the electrode lines are provided with standardized plugs, which engage in similarly standardized sockets of the cardiac pacemaker to produce the desired electrical connection. These sockets of the pacemaker are typically situated in a header of the pacemaker, manufactured from electrically insulating plastic, which is electrically connected via a bushing to the detection stage(s) and the stimulation pulse generator(s) in the interior of a sealed metal housing of the pacemaker. This metal housing additionally houses a battery for operating the pacemaker and control electronics. The stimulation pulse generators typically comprise capacitors in which the energy for a stimulation pulse is stored before delivery of a stimulation pulse. The capacitors are charged with the aid of a suitable charging stage, which acquires its energy from the battery of the pacemaker. Typically, a large part of this metal housing, if not even the largest part of the metal housing, is occupied by the battery of the pacemaker.
The present invention has the object of specifying a cardiac pacemaker which avoids many of the restrictions of the standard arrangement of a pacemaker presented here and thus opens up new fields of application for pacemaker treatment.